Antenna mast clamp



E. L. BARRETT ANTENNA MAST CLAMP Oct. 26, 1954 2 Sheets-Sheet 1 Filed June 7, 1951 mvizmwom-w (Edward L. ECXY'V'QW C 0295a,, ma

(HTIOIQAJELY/ Oct. 26, 1954 E. L. BARRETT 2,692,745

J ANTENNA MAST CLAMP Filed June 7, 1951 2 Sheets-Sheet 2 mow- relatively limited range.

Patented Oct. 26, 1954 UNITED STATES PATENT OFFICE ANTENNA MAST CLAIVIP trust Application June 7.1951, Serial No. 230,268

6 Claims.

The present invention relates generally to antennas and more particularly to television antenna supporting devices.

Because of the relatively high frequencies employed in the transmission of television signals, these transmissions are directional and are of In order to increase the possibility of signal reception, the receiving antenna should be mounted as high as practicable above the earths surface, and in order to attain maximum signal strengths from several transmitting stations within whose service areas the receiving antenna is located, it is desirable that the receiving antenna be rotatably mounted to the end that it can be properly oriented in the direction of the particular trans- .mitting station whose signal is to be received.

A supporting structure for a receiving antenna, therefore, should include provision both for rotating the antenna with respect to some fixed structure, such as a roof top, chimney, or the like, and also the adequate strength to sustain the antenna against the action of winds.

It is a general object of the present invention to provide a novel supporting structure for use between the fixed and rotatable portions of a mast for mounting a conventional television antenna which will accommodate various mast sizes yet is of exceedingly simple character and permits of economical manufacture.

Still another object of the invention is to provide an antenna mast supporting device which is operativeto prevent loosening of the mast sections when vibrated under the action of winds and which is operative to maintain coaxial relation between the fixed and movable mast sections regardless of the sizes of the sections.

The objects of the invention thus generally set forth, together With other objects and ancillary advantages, are attained by the construction and arrangement shown by way of illustration in the accompanying drawings, in which: t Figure 1 is a fragmentary perspective View showing a rotary joint structure and supporting means embodying the features of the pres 2 taken substantially in the plane of the line 6-6 in Fig. 1.

Fig. '7 is a fragmentary transverse section taken substantially in the plane of line 'l--l in Fig. 1.

While the'invention is susceptible of various modifications and alternative constructions, there is shown in the drawings and will herein be described in detail the preferred embodiment, but it is to be understood, however, that there is no intention to limit the invention to the form disclosed, but it is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

In accordance with the present invention, there is provided an antenna mast supporting structure for maintaining in upright coaxial relation fixed and rotatable mast sections and embodying means for gripping the mast sections which is capable of accommodating a relatively Wide range. of mast sizes. The coaxial supporting structure is effective, at the same time, to prevent loosening of the mast sections and to eliminate localized deformation of the mast sections which would result in weakening the same and making them liable to be bent as the antenna is subjected to wind action.

By way of illustration, there is shown in Fig. l of the drawings the joining means interposed between a fixed mast section l0 and a relatively rotatable mast section I 2. This means includes a housing l5 enclosing an electric motor together with upper and lower clamping portions I8, 20 for mounting the motor housing on the fixed mast section Hi and for mounting the rotatable mast section l2 on the motor housing l5. The motor and associated components disposed within the housing I5 form no part of the present invention. It willsuffice to say that the housing 15 rotates With respect to a pillar member I 4, the joint between them being sealed by rubber packing IT. For the details of this structure, reference is made to my copending applications Serial Nos. 230,266 and 230,267, filed June 7, 1951, and Serial No. 243,108, filed August 22, 1951, now Pat. 2,668,920.

The motor housing I5 is equipped with a coaxially disposed upwardly projecting post 19 which is adapted to be received in the lower end of the mast section I2. In order to accommodate masts of various internal diameters, the post I9 is equipped with a split conical bushing 2! having an axial bore therethrough for the reception of the post. t will be apparent from Fig. 2 of the drawings that masts of relaccommodation of masts atively small internal diameters will engage the bushing 25 adjacent the top thereof while masts of larger internal diameters will slip further down on the. collar.

The rotatable: mast i2 is mounted in coaxial relation on the motor housing 15 for rotation therewith by means of the supporting structure portion generally designated 25). The latter, in the present instance, includes an annulars-supporting member 22 in the. form of a contractile band or collar adapted to ,embracethewmotor housing IS, a collar 24 ion-grippingthe rotatable mast l2 together with three equally-spaced struts 23 serving to space the ;members -22- and 24 apart, maintain them in qcoaxialzrelation,z-zand are drawn together. sozasv to firmly grip the motor housing 15. In order to prevent: disengagement of the memberv 22 fromthemotorhousing; the latter is preferably; provided with r-a peripheral groove 2'? for the'reception .of thew-member 22.

Referring particularly to FigLB; itw-ill-be noted that the collarid: comprises-three segments. 28,

29 and 30. each havingqa central arcuate section;-

for disposition adjacent thexmastl2. :T-he central arcuate sectionsofnthecollar segments: 28,

. wand 30 are curved tocorrespondto, the average diameter of theyrangevof imast sizest-tonbe received therein. IThGLEIldS'LOf the sections 28, 29'

and 3t areturned-toutwardly and? are apertured for thexreception of bolt-'an'denut:fastenersfil. The struts. 23 are fixed .at theirxlower; ends to the outer surface of'lthe' collar 22 by welding or At theiriiupper. ends". the' struts. 23 are the like. rigidly secured to-Ithe.inner:ssurfaces of the arcuate. central sectionsrof. the: collarrsegmentsi'iit,

29 and 3t and are'ofaarcuatexform .to conform to the shape. of .zthe .rsegments. :Intermediate their ends the: strutsir23 'have. a longitudinal. strengthening ribt3lvprovided' tow'stiffenthe same.

It will be notedithatzzthe end-portions of the struts .23 which are respectively "hired to the collar sections 23,1 29 and 30 and to the member 22 lie-parallel to the :central 'axisof'the'whole mast assembly. Theseen'd portions are joined uwith .thenriibbed intermediate-portions or the strutsby relatively. smooth bendsas indicated at 33 (Fig.1), the 1'ibs 32 -terminating in spaced relation to" the bends.

The supporting structure portion- 20 permits 1 2 f various sizes. The sections 28, I 29 .an'd 3il of the gripping collar 2 1 may'bereadilyspread apart'ormoved together simply by r adjusting the b'olt-and-nut.

fasteners 3|. Uponreference to Fig.3, it will be seen that the curvature of the-intermediate segments of the collar -sections"28,29 andh'iirand of the upper ends of-the struts'32 issuchthat the ends of the strutsbear against the outer.

surface of the -mast throughout their entire widths for a-mast -section*having-' anaverage outer diameter or the range of mast-sectionsizes to be received therebetween. Thus upon "tightening the bolt-and-nut fasteners-'- 3|,- the mast I2:

will be uniformly -squeezed. -"I"his will result, upon continued tightening, inauniform squeezing of the'tubular mast .l 2.

In Fig. 4 there is shown the instant supporting structure portion 2G:.applied.-.to a mast section having an outer diameter smaller than that shown in Fig. 3. It will be apparent in this instance that the ends of the struts 32 bear against theouter surface. of themast in longitudinal line contact, .the contact. lines being spaced substantially apart, when the fasteners 3| are adjusted so that the inner surfaces of the upper ends of the struts are just brought ntoi-bearaagainst the outer mast surface. However, upon tightening the fasteners 3!, this line wcontact is changed into surface or ribbon contact at23a by the slight uniform deformation of the mastvasthe clamping pressure increases. Accommodationofthe smaller sized mast i2 re- .iqu-ires-an alteration of the angle of bend at 33 so that the upper ends. of the struts 32 extend ,,parallel to the mast so as to obtain full gripping thereof throughout the length of the ends of .theqstruts. Similar adjustment of the angle of the bands 33 is required to accommodate larger sized masts: l2.

As-shown in;Eig. .5,. theclarnpi-ng collar sections 28, 29 and 30 are. spread .apartto grip a mast-of such increased diameter. In view of the fact that thewarcuate-segments 'of the collar sections, 2 8;2Q'and'30 and theends of the struts 32-are made tofv averagencurvature, in thisrinstance there is line contact between the edges of the-ends of thestrutswith thesurfaccof the mast l2. Again, as the bolt-and-nut fasteners 3 L are tightened, there results uniform deformation-of.the-mastndueto the uniformly spaced .contact areas. As a result of-such deformation, .the', contact is transformed. from:line contact to ,a.ribbon.--surface engagement at six areas indicatedat: 23b.

The above :action 1532,11: important feature of the presentinvention. lt distinguishes the. operation "of the instant; structure from conventional-clamps employing set screw. arrangements .Whereingrippingis dependent upon awlocalized applicationofforce to the mast. As a result, adequate, tightening; exceeds the elastic limit. and produces-.a-localized deformation; which weakens the mast andq-causes itlto loosenwhen the am tenna structure is subjected :to -wind-action. .IJpon taking up: the'play, the'sameglooseningat the set screw is repeated regardless of howitight the set screwmightbe-setmSince tightening the set screw exceededythe elastic 1 limit of mast i-sectionat itspoint of contact, there: is little or uno-resi1ience afforded :by the mast. to accommoxdate wind-caused:yibrationwbetween' it. and the setscrew. rAsg-ai' result the deformation is. increased .and-themast: is again loose.

-With the present. mast supporting structure, howevergzthe rslight uniform deformation, which results from: therapplication of force equally distributed about the; mast section with relatively .large ribbon area :contactbetween'collar and mast,; permitsadequate tightening to obtain well withinxthe elastic limit .of'themast. Further- -m0re,1eVen"-if the: fasteners 3| be tightened so that: the unit .area: pressure produced causes the mast rtor take on .asmall amount of permanent .set, this onlyincreases :thecontact areato at least partially reduce unit area pressure and :thereresults 'IIlO progressive deforming and resulting loosening.

:It. is alsoapparent from the foregoing description that the struts 23-whichare reinforced through the-provision of the-strengthening ribs -32 are stifi" foralldiameters of maststo' be accommodated by the supporting structure. Since bending-bfthe strut'endportions to place the 5. same parallel to the mast axis is localized between the strut end portions and the strengthening ribs, occurring immediately adjacent the collars 22 and 24, the struts provide rigid connecting means acting in both tension and compression as braces between the collars. The present construction thus provides an exceedingly strong arrangement for supporting all mast sizes and in conjunction with the post and bushing 19, 2| serves to maintain the mast section supported therein in exact coaxial relation with the housing I5.

The supporting structure portion 18 whereby the rotary joint is secured to the fixed mast includes a number of the same features as the supporting structure portion 20 above described. Referring particularly to Figs. 1, 6 and 7, it will there be seen that the supporting structure portion 18 includes an annular supporting member 40 rigid with which are the ends of struts 42. The latter, in turn, support mast gripping collars 44 which are identical with the collar 24 of the supporting structure portion 20'. The lower ends of the struts are of arcuate form and are made rigid with the intermediate arcuate segments 48, 48 and 56 of the clamping collars 44. These outer strut ends are adapted toengage the outer surface of the fixed mast [0 to grip the same therebetween upon tightening bolt-and-nut fasteners The strut end portions, in this instance, however, are elongated and two of the collars 44 are provided so that adequate purchase on the fixed mast section II] obtains.

For this portion of the mast supporting structure, the annular supporting member 40 is of inverted cup-shape and is provided with a coaxial threaded hole 52 for the reception of a threaded stud 53 carried by the pillar I 4 which rotatably supports the motor housing [5.

In order to accommodate the upper ends of the struts 42, the annular supporting member 49 is necked-down to provide a peripheral shoulder against which the upper ends of the struts abut. The strut ends may be fixed to the member 40 conveniently by a welding operation.

It will be apparent upon reference to Fig. 7, that the lower ends of the struts 42 and the clamping collars 44 operate to grip fixed masts of various outer diameters in the same manner as the gripping collar 24 and upper ends of the struts 32 operate to grip various sizes of rotatable masts I2. The intermediate portions of the struts 42 are reinforced by ribs 54 and are joined to the end portions thereof by smooth double bends as at 55 which permit alteration of the angles thereof. Thus the lower ends of the struts 42 can readily be made to lie parallel to the mast axis regardless of the size of the mast so as to maintain the desired coaxial relationship.

Upon reference to Figs. 1 and 6, it will be seen that the intermediate portions of the struts 42 bridge the space between the lower end of the annular supporting member 40 and the upper end of the fixed mast portion I0. Thus they can be conveniently used for the support of auxiliary equipment such, for example, as a cable connector or junction box indicated generally at 6d, the same being fastened in place by any suitable stirrup-like strap, mounting screws or the like.

It will be apparent from the foregoing that a supporting device fashioned in accordance with the present invention and including a rotatable mast supporting portion and a fixed mast supporting portion for mounting the same on the fixed and rotatable elements of a rotary joint structure provides not only the rugged means required for joining the two mast sections together, but at the same time maintains them in coaxial relation regardless of the sizes of the mast sections employed. Gripping of the mast sections by means of the segmental collars and their bolt-and-nut fasteners makes use of the resilient character of the cylindrical tubing of which the mast sections are formed. As a result, actual contact between the segments of the gripping collar and the surfaces of the mast sections becomes a ribbon area contact as the mast sections are slightly deformed upon the tightening of fasteners. This eliminates any localized deformation of the mast sections which together with the rigid brace action of the struts insures against bending even if the antenna structure should be subjected to exceedingly severe winds.

I claim as my invention:

1. In an antenna rotator for interconnecting rotatable and nonrotatable antenna mast sections, the combination comprising, a cylindrical member, a generally bell-shaped housing coaxially and rotatably supported thereby, a plurality of downwardly extending struts having their upper ends secured to said member, a segmental clamping collar embracing said struts for clamping the latter against the nonrotatable mast section, an axial centering post extending upwardly from said housing for receiving the low er end of the rotatable mast section, a plurality of upper struts having their lower ends secured to the upper periphery of said housing and extending upwardly and inwardly on an incline therefrom, and a segmental clamping collar for clamping the upper ends of the upper struts against the rotatable mast section.

2. In an antenna rotator for supporting a tubular antenna mast, the combination comprising, a generally bell-shaped housing, means for rotatably supporting the housing, an axial up wardly tapering post for receiving the lower end of the mast, a segmental clamping band embracing said housing, a plurality of fiat struts secured to said band and extending upwardly and inwardly on an incline therefrom, and an ad justable segmental collar embracing the upper ends of said struts for clamping the latter against the mast.

3. In an antenna rotator for connecting an antenna mast to a stationary mast, the combination comprising, a cylindrical member, means rotatably carried on said member for supporting the antenna mast, said member having an axial downwardly opening socket, a plurality of struts secured to the member and extending downwardly therefrom, said struts having transversely curved lower portions for engaging the stationary'mast, and a pair of segmental clamping collars embracing said curved lower portions of said struts for clamping the latter against the stationary mast, said struts having fiat portions between said collars and said member to provide for fiexure of said struts to accommodate various sizes of stationary masts.

4. In an antenna rotator for interconnecting rotatable and non-rotatable antenna mast sections, the combination comprising, a cylindrical member, a generally bell-shaped housing coaxially and rotatably supported thereby, means for rigidly mounting said member at the top of said non-rotatable mast section and coaxial therewith, an axial centering post extending upwardly from said housing for receiving the lowaeeame of upper, struts "having: their: lower. ends; secured toxthenupper periphery ofjsaid: housing and extending upwardlyr-andinwardly on an incline therefrom, andi a; segmental clamping means for ciampingthe; upperr endsof the upper struts againsttthe rotatablewmas-t section in symmetrically spaced relation.

5; Inxan antenna-:rotatorgforsupporting a tubular; antennai mast; the combination comprising, E'35'61'161'3EHX; bell-shapedzhousing, 'means for rotatably supporting the housing, an axial upwardly:taperingpostfor receiving the lower end ofr'the,masthaiplurality of struts for coupling said; housing. and. said tubular antenna mast, means; for; anchoring;v the lower ends of said struts; rigddlya to; the periphery of said housing an'd' 'symmetrically spaced thereabout so that the struts extend upwardlyvandsinwardly therefrom, each of said struts providing a pair of radially extendingzears-at its upper end and with the ears on-adjacent struts being arranged in pairs opposite one another, and means including a threaded boltrfor engaging each pair of ears for drawing the ears clampingly toward one another;

6. In an antenna rotator-for connecting an antennaimastto, a stationary'mast, the combination comprising; a cylindrical member, means rotatahlyacarriedzonzsaidzmember; for; supporting: the 1 antenna: mast; a: plurality of struts secured.

to the member and extending :downwardly there-v from, said struts 'havingztransversely curyedrlower portions; for; engaging; the; stationary mast; and a pair: of segmental: clamping collars em, bracing saidvcuryedslower:portions of saidistruts for clamping the latter: against the stationary mast the central portions of 1 said struts being longitudinally,formedjntoxchannel shape to provide longitudinal rigidity, .sa-id'str-uts having fiat:

unchanneled portions at each end offsaid central portion for. localized bending: of the strut about aztransverse axis therebyrtoaccommodate;

various sizes of stationary; masts;

References Cited in; the -.fi1e' of a this patent UNITED 1 STATES PATENTS Number; Name Date 931,610 Bolsterli Jan. 1'7; 1911,

1,662,519 Kirshner Mar. 13, 1928 2,448,304 Gab'elI Aug. 31, 1948 2,498;957 Jordan Feb. 28; 1950 FOREIGN= PATENTS Number Country Date 421440 Switzerland Aug.- 20', 1908 

